A new change to the Criminal Code that makes it illegal to wear a mask at a protest or riot is likely to be challenged in the courts as limiting freedom of expression, experts say.

The clause makes it a crime for a person to attend an unlawful protest “while wearing a mask or other disguise to conceal their identity without lawful excuse.” Supporters say it is one more tool to help the police maintain order, while civil liberties advocates say it tramples constitutional freedoms.

“It’s outrageous, there’s all kinds of legitimate reasons to mask your face in terms of a protest,” said Micheal Vonn, policy director with the British Columbia Civil Liberties Association.